The invention relates generally to the dispensing of visco-elastic fluidic materials, and more particularly to methods for producing vacillating visco-elastic fibers for application onto substrates and elongated strands, and combinations thereof.
It is desirable in many manufacturing operations to form visco-elastic fibers or filaments, which are deposited onto substrates and elongated strands moving relative thereto. These operations include the application of fiberized adhesives, including temperature and pressure sensitive adhesives, onto substrates and elongated strands for bonding to substrates. Other operations include the application of nonbonding fiberized visco-elastic materials onto various substrates as protective overlays, for example onto sheet-like articles which are stacked or packaged one on top of another, whereby the non-bonding fiberized material provides a protective overlay or separating member between the stacked articles.
One exemplary bonding operation is the application of substantially continuous adhesive fibers onto woven and non-woven fabric substrates for bonding to other substrates and for bonding to overlapping portions of the same substrate in the manufacture of a variety of bodily fluid absorbing hygienic articles. The adhesive fibers may also be applied to elongated elastic strands for bonding to portions of the substrate, for example in the formation of elastic waste and leg band portions of diapers and other undergarments. Another exemplary adhesive fiber bonding operation is the bonding of paper substrates and overlapping portions of the same substrate in the manufacture of paper packaging, for example disposable paper sacks.
In many adhesive fiber bonding operations, including the exemplary bodily fluid absorbing hygienic article and paper packaging manufacturing operations, as well as many non-bonding operations, it is desirable to uniformly apply the visco-elastic fibers onto the substrate and to accurately control where on the substrate the visco-elastic fibers are applied. The uniform application of visco-elastic fibers onto substrates and elongated strands ensures consistent bonding between substrates, or overlapping layer portions thereof, and elongated strands. The uniform application of visco-elastic fibers onto substrates and elongated strands also economizes usage thereof. Accurately controlling where the visco-elastic fibers are applied onto the substrate ensures proper and complete bonding in areas where bonding is desired, provides a distinct interface between areas of bonding and non-bonding, and generally reduces substrate waste resulting from visco-elastic fibers applied uncontrollably to areas thereof outside or beyond the desired target or bonding areas.
In the manufacture of bodily fluid absorbing hygienic articles, it is desirable to provide maximum absorbency and softness of overlapping bonded substrates and at the same time provide effective bonding therebetween. It is also desirable to bond stretched elongated elastic strands relatively continuously along the axial length thereof for bonding onto substrates so that the stretched strands do not slip, or creep, relative to the substrate when the substrate and strand are later severed in subsequent fabrication operations. More generally, it is desirable to accurately and uniformly apply visco-elastic fibers onto substrates and elongated strands, without undesirable overlapping of adjacent fibers, and with well defined, or distinct, interfaces between substrate areas with and without fiber coverage. Similar results are desirable in the application of bonding and non-bonding fibers onto substrates and elongated strands used in operations besides the exemplary manufacture of hygienic articles.
In the past, visco-elastic fibers have been applied onto substrates with melt blowing and spiral nozzles. Conventional melt blowing and spiral nozzles however do not adequately satisfy all of the requirements in the manufacture of bodily fluid absorbing hygienic articles and other operations discussed generally above, or do so to a limited extent using adhesive excessively and inefficiently. Melt blowing nozzles generally dispense fibers chaotically in overlapping patterns, and spiral nozzles dispense fibers in overlapping spiral patterns. The fiber patterns produced by these conventional nozzles tend to stiffen the substrate, which is particularly undesirable in the manufacture of bodily fluid absorbing hygienic articles. The fiber patterns produced by conventional nozzles also tend to reduce the puffiness and hence softness of bonded substrates, or fabrics, which reduces the comfort thereof. Additionally, fiber patterns produced by conventional nozzles tend to reduce the absorbency of fabrics by obstructing the flow of moisture between layers, usually from the inner layers toward more absorbent outer layers. The conventional nozzles also apply fibers onto the substrate relatively non-uniformly, and lack precise control over where the fibers are applied onto substrates and elongated strands.
The present invention is drawn toward advancements in the art of producing visco-elastic fluidic material flows, and more particularly to methods for producing vacillating visco-elastic fibers for application onto substrates and elongated strands, and combinations thereof.
It is an object of the invention to provide novel methods for producing vacillating visco-elastic fluidic material flows for application onto various substrates and elongated strands and combinations thereof that overcome problems in the art.
It is another object of the invention to provide novel methods for producing vacillating visco-elastic fluidic material flows for application onto various substrates and elongated strands and combinations thereof having one or more advantages over the prior art, including relatively improved control over where the fibers are deposited onto substrates and elongated strands, relatively uniform application of the fibers onto substrates and elongated strands, and economizing usage of the fibers and drawing gases associated with the application thereof.
It is another object of the invention to provide novel methods for producing vacillating visco-elastic fibers for application onto various substrates and elongated strands and combinations thereof, especially in the manufacture of bodily fluid absorbing hygienic articles. And it is a related object to provide bodily fluid absorbing hygienic articles having well bonded woven and/or non-woven substrates with improved absorbency and softness.
It is a more particular object of the invention to provide novel methods for producing visco-elastic fluidic material flows comprising generally drawing a visco-elastic fluidic material with corresponding separate second fluid flows associated therewith to form a visco-elastic fiber vacillating in a repeating, generally omega-shaped pattern having a bowed portion with first and second side portions that first converge toward each other and then diverge outwardly in generally opposing directions.
It is another more particular object of the invention to provide novel methods for producing visco-elastic fluidic material flows comprising generally drawing a visco-elastic fluidic material with corresponding separate second fluid flows associated therewith to form a visco-elastic fiber vacillating in a repeating, generally omega-shaped pattern, and depositing the vacillating visco-elastic fiber onto substrates and/or elongated strands moving relative thereto, and combinations thereof. It is a related object of the invention to deposit the vacillating visco-elastic fiber onto one or more stretched elongated elastic strands disposed on a substrate for adhering, or stitching, the stretched elongated elastic strands to the substrate substantially continuously along the axial length thereof.
These and other objects, aspects, features and advantages of the present invention will become more fully apparent upon careful consideration of the following Detailed Description of the Invention and the accompanying Drawings, which may be disproportionate for ease of understanding, wherein like structure and steps are referenced generally by corresponding numerals and indicators.